This book is a must for every engineer or designer engaged in electrical applications or products design. The objective of all the electrical safety measures is to avoid both electric shock and that the leakage currents exceed certain safety values. In this book, first we will explain basic concepts and definitions, then we will proceed with practical calculation examples of clearance and creepage distances for double and reinforced isolation taking as an example a food mixer appliance design. We will also talk about solid insulation in a specific chapter, with an example on how to choose a solid barrier or enclosure. Finally we will introduce insulation diagrams, a simple and powerful representation tool that is often neglected. Internatinal Standards are used worldwide by governments for regulatory purposes and generally to set up a bottom line for safety requirements, so we will refer to them throughout the book. The Author is a professional involved in everyday works on the matter and has used a double approach: - Theoretical definitions (being kept to what essential is) and - A practical example to explain calculation procedures with the paramount objective to keep it short and practical.